• 한국전산유체공학회:학술대회논문집
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• 2002.05a
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• pp.115-120
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• 2002

A two-dimensional direct numerical simulations was peformed to investigate the flame structure of $CH_4/N_2$-Air counterflow nonpremixed flame interacting with a single vortex. The detailed transport properties and a modified 16-step augmented reduced mechanism based on Miller and Bowman's detailed reaction mechanism were adopted in this calculation. To quantify the strain on flame induced by a vortex, a scalar dissipation rate (SDR) is introduced. Results show that the fuel- and air-side vortex cause an unsteady extinction. In this case, the flame interacting with a vortex is extinguished in much larger SDR than steady flame. It was also found that air- side vortex extinguishes a flame more rapidly than fuel -side vortex.

• Archives of Plastic Surgery
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• v.38 no.6
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• pp.875-878
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• 2011

Purpose: Absorbable implants are frequently used to fix facial bone fractures, because they are radiolucent and compatible with magnetic resonance imaging (MRI). Despite their increasing usage, however, there have been few reports about their long-term side-effects. In this paper, a case in which absorbable implants led to a foreign body reaction 17 months after their insertion is presented. Methods: A previously healthy 19-year-old male fell from a flight of stairs and visited the authors' hospital with right periorbital pain. Zygomaticomaxillary fracture involving right orbital floor was detected via a facial bone computed tomography (CT). Internal fixation with absorbable implants was followed by open reduction. 17 months after the surgery, the patient complained of localized periorbital swelling. Removal of the granulomatous lesion including the absorbable implants along with their biopsy and culture was performed. Results: The granulomatous lesion around the implants was firm and extended into the maxillary sinus. The histologic finding showed a microabscess with a foreign body reaction. Methicillin-sensitive Staphylococcus aureus growth was confirmed in the culture. No definite abnormal symptoms ensued after the complete removal. Conclusion: A microabscess-forming granulomatous lesion around the absorbable implant can cause delayed symptomatic foreign body reaction despite its rare occurrence. Complete removal of the lesion including implants is expected to have a successful outcome if it is encountered.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.3 no.2
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• pp.116-121
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• 2017

To overcome the low reactivity and solubility of alkali metal fluorides (MFs), various types of phase transfer catalysts (PTCs) have been developed over the last decades. However, since the fluoride activated by such PTC sometimes has a strong basicity, it may cause various side reactions such as elimination reaction or hydroxylation reaction in the nucleophilic fluorination reaction. Also, they may cause separation problems in the compound purification process. In recent advanced study, various PTCs have been developed to solve these problem of conventional catalyst. In this review, we would like to introduce three kinds of novel multifunctional organic catalysts such as bis-tert-alcohol-functionalized crown-6-calix[4]arene (BACCA), easy separable pyrene-tagged ionic liquid (PIL) by reduced graphene oxide (rGO), and tri-tert-butanolamine organic catalyst.

• Proceedings of the KWS Conference
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• 2006.10a
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• pp.169-171
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• 2006

Solderability and reaction properties were investigated for four Pb-free alloys as a function of Ag contents; Sn-4.0Ag-0.5Cu, Sn-3.0Ag-0.5Cu, Sn-2.5Ag-0.5Cu, and Sn-1.0Ag-0.5Cu. The alloy of the lowest Ag content, i.e., Sn-1.0Ag-0.5Cu, showed poor wetting properties as the reaction temperature decreased to 230oC. Variation of Ag concentration in the Sn-xAg-0.5Cu alloy shifted exothermic peaks indicating the undercooling temperature in DSC curve. For the aging process at 170oC, the thickness of IMCs at the board-side solder/Cu interface increased with the Ag concentration.

• 연구논문집
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• s.27
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• pp.175-181
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• 1997

Superconducting joints between Bi-2223/Ag tapes are fabricated by a press & reaction anneal and a multiple press & anneal. The silver sheath was mechanically or chemically removed from one side of each tape without altering the superconducting core. The exposed superconducting core of the two tapes were brought into contact and pressed so as to form a lap joint. The joined tapes were then subjected to a series of different thermomechanical treatments to achieve optimum heat treatment condition. The result from transport measurements shows that critical current ($I_c$) transmitting through joined area reaches 9A, approximately 60% of the current capacity of the tapes themselves. The critical current through joined area was improved by repeated press and reaction annealing. Measurements of the current-voltage relationship were made with several configuration of the voltage probes to characterize the critical current variation and I-V curve along the joint. Also discussed are microstructural aspects of the superconducting joint.

• Journal of Pharmaceutical Investigation
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• v.22 no.1
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• pp.23-31
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• 1992

A novel O-diethylaminoethyl chitosan (DEAE-chitosan) was synthesized via Schiff's reaction between chitosan and benzaldehyde. $C_2$ amino group was protected via Schiffs base reaction with benzaldehyde to form N-benzylidene chitosan. After reaction with diethylaminoethyl chloride, Schiffs base was removed by reacting O-diethylaminothyl-N-benzylidene chitosan and hydrochloric acid. Tensile strength of DEAE-chitosan was improved due to the incorporation of bulky side group in $C_6$ position of chitosan. DEAE-chitosan showed a pH-dependent swelling characteristics. Release rate of riboflavin was dependent on the water content of DEAE-chitosan that is a function of crosslinking degrees.

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.5
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• pp.612-619
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• 2016

Pitch synthesis reaction was studied based on the effect for chemical composition of feedstock. Feedstock was selected as pyrolyzed fuel oil (PFO) and coal-tar (CT), which are by-products in petroleum and steel industry. Pitch was prepared at $420^{\circ}C$ for 180 minutes on atmospheric pressure by thermal treatment. Thermal stability and softening point (SP) of the prepared pitches were investigated and their molecular weight distribution was analyzed by MALDI-TOF. PFO has various aliphatic compounds and coal-tar has high aromaticity with 3 wt% of primary quinoline insolubles. The thermal property of PFO was enhanced with polymerization reaction during the thermal treatment with increased molecular weight range. But CT was inferior to PFO because of side reaction by hetero elements. CTP was appeared molecular weight by 0~200 m/z.

• Korea-Australia Rheology Journal
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• v.17 no.4
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• pp.199-205
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• 2005

Carbon dioxide was absorbed into aqueous polyethylene oxide (PEO) solution containing AMP in a flat-stirred vessel to investigate the effect of non-Newtonian rheological behavior of PEO on the rate of chemical absorption of $CO_2$, where the reaction between $CO_2$ and AMP was assumed to be a first-order reaction with respect to the molar concentration of $CO_2$ and AMP respectively. The liquid-side mass transfer coefficient, which was obtained from the dimensionless empirical equation containing the properties of viscoelasticity of the non-Newtonian liquid, was used to estimate the enhancement factor due to chemical reaction. PEO with elastic property of non-Newtonian liquid made the rate of chemical absorption of $CO_2$ accelerate compared with Newtonian liquid based on the same viscosity of the solution.

• Nuclear Engineering and Technology
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• v.50 no.7
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• pp.1184-1189
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• 2018

Pyroprocessing uses various molten salts during electrochemical unit processes. Reaction products after the electrochemical processes must contain a significant amount of residual salts to be separated. Vacuum distillation is a common method to separate the residual salts; however, its high operation temperature may cause side reactions. In this study, a simple rotation technique using centrifugal force was suggested to separate the residual salts from the reaction products at relatively low temperature compared to the distillation technique. When a reaction product container with porous wall rotates inside a vessel heated above the melting point of the residual salt, the residual salt in the liquid phase is separated through centrifugal force. It was shown that the $LiNO_3-Al_2O_3$ mixture can be separated by this technique to leave solid $Al_2O_3$ inside the container, with a separation efficiency of 99.4%.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1762-1764
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• 1999

We investigated the annealing effect on generating pretilt angle and aligning liquid crystal (LC) using the photo-depolymerization reaction in this study. In case of rubbing polyimide (PI) surface with the side chain, pretilt angle tends to increase with increasing the annealing time. It is considered because the steric interaction is increased by annealing which cause the side chain to come back to original position. For obliquely irradiating ultraviolet (UV) light on PI surface, pretilt angle shows to $0^{\circ}$ and is increased by annealing. The pretilt angle in rubbed PI surface is much higher than in photo-aligned PI surface. It is attributed to the steric interaction and the number of LC molecular arrangement on azimuthal direction. In addition. in case of obliquely irradiating UV light on PI surface. it showed LC alignment to increase by annealing. It can be regarded due to the fact that the re-alignment of LC molecule is improved to residual polymer direction by annealing.